Crazy Idea, but bare with me.... It's obvious that with my Z, and with other Z's there is the possibilty for oil to commonly make its way into the plenum chamber and thus into the combustion chamber. so, given that there was a small build up of oil on my air inlet manifold, which correct me if i'm wrong, but if oil is lining the manifold walls, then it could get into the chamber and cause fouling of the plugs. (yes/ no?) then wouldnt it be almost logical to have a filter, filter the air as it passes from the plenum into the inlet manifold? I was looking at in line air filters to place somewhere between the turbo's and the throttle bodies. but oil can get into the plenum from a lot more places than just the inlet piping. but then I thought, what If I buy some good quality air filter sheet, cut it to the shape of the plenum/ inlet manifold gasket and use that as a filter/ gasket for the plenum to prevent any oil from getting into the combustion chamber? yes, it might need to be replaced every 5,000k's, but that would be cheaper than replacing fouled plugs at $70 a set. :agree: :W: OR :bash:
Overthinking it. Most of the oil will be oil mist coming from the crankcase through the pcv valves. I have a VTA catch can so I don't get any oil in the plenum but it wouldn't be the cause of fouling plugs anyway
Oil will always get into the chambers regardless as there is always some small amount of seepage past the oil ring and piston rings at the least and its more prevalent the thinner the oil viscosity. However excessive carbon deposits on plugs are more likely to come from a richer fuel mixture unless you have a major oil leak somewhere. So oil residue in the plenum shouldn't be a major problem for plugs unless its really excessive (i.e. turbo's are shot in which case they would be the problem and not the plugs). You can clean the carbon off the plugs to a certain degree. Its good your thinking outside the box even if its not practical as this is how we sometimes can improve things from thinking outside the box but when the plugs are shot, just bite the bullet and pay the $70 ! Another option however is also to use a small amount of suburu upper engine cleaner on a reasonably regular basis as opposed to a full can at service intervals, it will to a fair degree keep your plenum, valves and plugs clean. Its actually now part of the suburu engine service and it has a very good reputation for getting the engine clean of carbon build-up hence why its part of the suburu service now. Just make sure you only use it where you don't mind the concrete getting dirty at the tailpipe area, the amount of carbon it will release is impressive (and very dirty) to say the least! In the U.S its known as seafoam. Even most old hard school mechanics that believe only oil and fuel should go into an engine tend to accept it is a useful product if used carefully. Hope that's of some help to you Regards JC
Oh no! Someone must have hacked my account and posted this thread! How embarrasing and destructive to my reputation :/ Plenum filters... pfft! What a troll!! But while we're here. how does that subaru upper engine cleaner work super z? do you spray it in the plenum or how is it applied? Sounds like its worth a shot...
Don't worry about the hacking! Happens to us all :rofl: The suburu cleaner is sprayed via a small thin tube directly into the throttle body past the intake hoses whilst the engine is running - you then do the other side. You should be able to see it in action on youtube under suburu upper engine cleaner or seafoam. I have found it personally impressive in cleaning the carbon and any residue, so I keep a can handy on my garage in case I see some serious fouling JC
